This invention relates to a telecommunications system, to a method of charging some or all of the cost of a call to a callee, a method of debiting a prepay account of a telecommunications subscriber and to telecommunications apparatus.
Currently, in the field of telecommunications systems, a number of charging approaches exist, by which the cost of a call is determined and charged. Usually, the cost is borne by the caller, although it is also possible to make “collect” calls (otherwise known as “reverse charge” calls) where the cost of the call is borne by the recipient.
U.S. Pat. No. 4,933,966 describes a telephone system which uses a microprocessor control system, a speech generator and speech memory to automatically place collect calls without the need of a live operator. The microprocessor control system and a speech record/playback generator are used to receive a destination number and a recorded name from a user. The speech generator is used to play audio messages to prompt the user throughout the process. A called party is informed via synthesized speech messages of the identity of the user. Responses from the called party are received through a DTMF receiver. A communication path is established through a telephone line interface if the phone receives a response indicating that the called party accepts the charges for the collect call. The microprocessor control system generates a billing record of the call which is stored in a call record memory.
U.S. Pat. No. 6,138,006 describes a technique for informing a called mobile station operating in a visited mobile switching centre (V-MSC) that an incoming call is a collect call prior to delivering the incoming call to the mobile station. The system obtains, in an originating mobile switching centre (O-MSC), a collect call prefix from a calling party and determines from the collect call prefix that the incoming call is a collect call. A collect call indication (CCI) is generated and sent along with the calling number to the V-MSC in a Location Request (LocReq) Invoke message and a Routing Request (RoutReq) Invoke message, thereby notifying the V-MSC that there is an incoming call for the mobile station and that the incoming call is a collect call. The V-MSC sets a collect call flag to ON, stores the calling number in a subscriber record in the V-MSC, and determines whether the mobile station is a digital mobile station. If so, a Short Message Service (SMS) message including the calling number is sent to the mobile station informing the subscriber that the incoming call is about to be delivered and that the incoming call is a collect call. If the mobile station is a dual-capable mobile station, a distinctive ringing signal is sent to the mobile station. The incoming call is then delivered to the mobile station, and the subscriber may choose to answer or not. The collect call flag is then reset to OFF in the subscriber record in the V-MSC.
Moreover, systems in which calls are selectively billed to the caller or to the callee at the election of the callee are known. For instance, in the context of a cellular telephone system in which callees must pay for incoming calls, U.S. Pat. No. 5,473,671 describes a divergent call treatment technique which involves a list of accepted callers that is provided by the subscriber and maintained in a database by a service provider. When a call comes in, a determination is made as to whether the caller is an “accepted” caller. If so, the call is forwarded to the cellular telephone. Otherwise, the caller is offered the option to pay for the call. A willingness on the part of the caller to pay for the call is indicated by a signal from the caller, such as pressing a key on a DTMF pad. In response to such a signal, the call is forwarded to the cellular telephone. In the absence of such a signal, the call is disconnected or diverted.
Telecommunication systems that allow a subscriber to prepay for services have recently become popular. The advantage for the service provider of prepay arrangements, which are usually provided in relation to cellular or wireless systems, is that the service provider obtains payment in advance, saving costly collection services and the need to obtain security such as credit card information from the subscriber. For the subscriber, the advantage is that the subscriber pays as the system is used, thus avoiding basic monthly service charges when usage is low.
A feature of many such systems is that prepaid airtime has validity that is limited in time, so that prepaid airtime not used before the end of a billing period is lost. The advantage of this arrangement for the service provider is that some continual revenue income from subscribers is ensured, in that even subscribers with very low usage need to purchase at least some prepaid time in each billing period, in order to maintain their account “active”. However, the feature gives subscribers the impression that airtime which has been paid for may inadvertently be being lost and that some subscribers may in practice be being forced to purchase services that they neither want, use nor need.
The present invention is directed to providing a telecommunication system in which subscribers can be given greater control and flexibility in relation to how prepaid airtime is used and which allows them more easily to ensure full use of their own prepaid airtime. The system may also in at least some circumstances have advantages for the service provider in that it allows the actual use of airtime to be estimated more accurately on the assumption that all airtime that has been paid for will actually be used.